contraception

The use of devices or techniques to prevent pregnancy.
Oral contraceptives include the female contraceptive pill,
a hormone preparation containing synthesized estrogen
and progesterone, which prevents ovulation
– the release of an ovum (egg) –
and thickens the cervical mucus thereby reducing the chances of fertilization
should ovulation take place. The convenience and efficacy of the various
versions of the "pill" make it the most reliable form of contraception available,
although it has been associated with some serious and some minor side-effects
and should be prescribed on an individual basis.

Development of a male pill, containing testosterone
and progestin is underway. Although initial tests have shown that it is
effective in reducing sperm count, it will not be available for some years.

Barrier contraceptives include the male and female
condom and the diaphragm. The male condom is a latex sheath which covers
the penis and collects the ejaculated the
semen; the female condom lines the inside
of the vagina, preventing any sperm entering
the uterus. The use of condoms is widely
advocated because they help protect against some sexually transmitted diseases,
including acquired
immune deficiency syndrome (AIDS). Devices such as diaphragms and caps
cover cover the cervix thus preventing sperm
entering the uterus. The intra-uterine device (IUD) is a small spring made
from plastic or metal inserted into the uterus. It stops the fertilized
egg embedding itself in the uterine lining.

Emergency contraception, known as the morning-after pill, can be taken up
to 72 hours after unprotected sexual intercourse; it prevents the fertilized
ovum embedding itself in the uterus. It is not suitable to be used regularly.

Techniques to prevent pregnancy include the so-called "rhythm method". This
involves the avoidance of intercourse on days when contraception is most
likely (when the woman is ovulating). It is not a reliable method because
ovulation cannot always be predicted accurately. Another technique if coitus
interruptus – the withdrawing of the penis from the vagina before
ejaculation. This is also very unreliable as small amounts of semen are
also released from the penis before ejaculation.